Dr Stephen Bolsin is the man widely credited with blowing the whistle on Bristol - endangering his own future in the process.

He claims he was virtually driven out of medicine in this country after proving the catalyst for the ensuing scandal.

But what drives a relatively junior consultant anaesthetist to take the extreme step of risking everything in this way?

Dr Bolsin's own words sum it up: "In the end I just couldn't go on putting those children to sleep, with their parents present in the anaesthetic room, knowing that it was almost certain to be the last time they would see their sons or daughters alive."

I got the impression he'd been told his career would be under threat if he persisted

Dr Andy Black, of Steve Bolsin

Campaigner Maria Shortis told BBC News Online how she arranged to meet Bolsin on seeing him quoted in a newspaper in 1995.

Bolsin was doing the unthinkable - accusing his own team of failing the very babies it was trying to save.

She said: "When I read it, I thought: 'My God - this guy's just lost his job."

However, it had been a long journey to reach this point.

The young anaesthetist arrived from London's Royal Brompton Hospital in 1988.

He says he noticed almost straight away that operations seemed to be taking much longer in his new hospital.

He also suspected that death rates were higher - but had no firm evidence of this.

Confrontation

The young doctor raised the issue, briefly, in a letter to hospital trust chief executive Dr John Roylance.

There followed, he claimed, a confrontation with surgeon James Wisheart - denied by the older man - the effect of which was to make Bolsin fear for his career in Bristol.

Fellow anaesthetist Dr Andy Black said that he noticed him getting depressed - and preparing even to leave the hospital.

"I heard Steve was planning to apply for an Oxford job - he told me he was dissatisfied, he told me he didn't think the results were very good in Bristol.

"He told me he'd tried to raise it - I got the impression he'd been told his career would be under threat if he persisted."

Black told Bolsin that if he had a problem, he should get some figures, and then helped him put them together.

The now notorious audit they constructed set the foundations for the explosion of the scandal.

It revealed evidence of deeper problems - put simply, it suggested too many babies were dying.

Armed with this explosive document, he set off to change the way the paediatric cardiac team regarded its work.

Divided opinions

Black says he always regarded Bolsin as "highly principled", but, just as the Bristol scandal divided medical opinion across the city, there are many who feel that he did not approach the situation in a way that was fair to the surgeons.

While many parents and some doctors eulogise him, others have demonised him.

Many have accused him of leaking damaging stories about Bristol to the satirical magazine Private Eye.

The anaesthetist admits meeting Eye columnist Dr Phil Hammond - then a trainee GP from Taunton - but says he did not know that he was the anonymous contributor, and strenuously denies the accusation.

James Wisheart says he never got the chance to view the completed audit until two years after it was completed.

But many senior figures - including the chief executive - knew of its existence, and yet its apparently damning results were never openly discussed.

After the scandal broke in 1995, Steve Bolsin tried to get jobs elsewhere in the UK, feeling that, as a whistleblower, he could no longer work on at Bristol.

But, failing to secure one, he decided more drastic measures were needed.

In something close to a "moonlight flit", he secretly applied for, and landed, a job at Geelong Hospital in Australia.

Here his career has been revived, but he is never far from the shadow of Bristol - giving evidence by video-link last year.

Steve Bolsin probably did not anticipate how his simple, unfocused query about death rates at Bristol would escalate into a key role in one of the great medical scandals of this century.